diff --git a/algorithms-sorting/src/main/java/com/baeldung/algorithms/shellsort/ShellSort.java b/algorithms-sorting/src/main/java/com/baeldung/algorithms/shellsort/ShellSort.java new file mode 100644 index 0000000000..c130e2d866 --- /dev/null +++ b/algorithms-sorting/src/main/java/com/baeldung/algorithms/shellsort/ShellSort.java @@ -0,0 +1,20 @@ +package com.baeldung.algorithms.shellsort; + +public class ShellSort { + + public static void sort(int arrayToSort[]) { + int n = arrayToSort.length; + + for (int gap = n / 2; gap > 0; gap /= 2) { + for (int i = gap; i < n; i++) { + int key = arrayToSort[i]; + int j = i; + while (j >= gap && arrayToSort[j - gap] > key) { + arrayToSort[j] = arrayToSort[j - gap]; + j -= gap; + } + arrayToSort[j] = key; + } + } + } +} diff --git a/algorithms-sorting/src/test/java/com/baeldung/algorithms/shellsort/ShellSortUnitTest.java b/algorithms-sorting/src/test/java/com/baeldung/algorithms/shellsort/ShellSortUnitTest.java new file mode 100644 index 0000000000..91a27c41d0 --- /dev/null +++ b/algorithms-sorting/src/test/java/com/baeldung/algorithms/shellsort/ShellSortUnitTest.java @@ -0,0 +1,17 @@ +package com.baeldung.algorithms.shellsort; + +import static org.junit.Assert.*; +import static org.junit.Assert.assertArrayEquals; + +import org.junit.Test; + +public class ShellSortUnitTest { + + @Test + public void givenUnsortedArray_whenShellSort_thenSortedAsc() { + int[] input = {41, 15, 82, 5, 65, 19, 32, 43, 8}; + ShellSort.sort(input); + int[] expected = {5, 8, 15, 19, 32, 41, 43, 65, 82}; + assertArrayEquals("the two arrays are not equal", expected, input); + } +}